The present invention relates to a thermoplastic resin composition which has an excellent fluidity and is able to form a molded product having a high elasticity.
In order to increase the modulus of elasticity of a molded product obtained from a thermoplastic resin, there has been already adopted a method where a filler such as carbon fiber, glass fiber, talc and mica is added. Among these fillers, carbon fiber has been used as the most effective means since the modulus of elasticity inherent thereto is very high and an effect of improving the modulus of elasticity resulting from its addition is high.
However, carbon fiber has a low specific gravity and, when its adding amount increases, its volume fraction in the resin significantly increases as compared with other fillers. Accordingly, as a result, fluidity of the resin lowers and the molding processability lowers. Especially in the case of molded substances (products) obtained from a material where high rigidity is required, many of them are then and, if the fluidity is low, there is a problem in processing. In addition, when reinforcement is carried out by a fibrous filler such as carbon fiber, there is another problem that warping caused by anisotropy in the shrinking rates arises.
An object of the present invention is to provide a thermoplastic resin composition which has none of the above-mentioned problems, shows a good molding ability due to its excellent fluidity and is able to yield a molded product having a high elasticity.
The present invention provides a thermoplastic resin composition comprising 90-30% by weight of (A) a thermoplastic resin, 5-60% by weight of (B) a fibrous filler and 5-60% by weight of (C) a whisker.
Examples of the thermoplastic resin which is the component (A) used in the present invention is one or more selected from a group consisting of a polyamide, styrene polymer, polyester, polyurethane, polyether, polyester ether, polyamide ether, polyphenylene oxide and polycarbonate. Among them, one or more selected from a styrene polymer, polyamide, polyester and polycarbonate are preferable, and a polyamide and a styrene polymer are more preferable.
As the polyamide, one or more selected from a polyamide resin formed from a diamine and a dicarboxylic acid and copolymers thereof such as Nylon 66, polyhexamethylene sebacamide (Nylon 610), polyhexamethylene dodecamide (Nylon 612), polydodecamethylene dodecamide (Nylon 1212), poly-m-xylylene adipamide (Nylon MXD6), polytetramethylene adipamide (Nylon 46) and mixtures and copolymers thereof; a copolymer such as Nylon 6/66, Nylon 66/6T, where a 6T component is not more than 50 molar % (6T: polyhexamethylene terephthalamide), Nylon 66/6I, where a 6I component is not more than 50 molar % (6I:
polyhexamethylene isophthalamide), Nylon 6T/6I/66 and Nylon 6T/6I/610; aromatic polyamide resin such as polyhexamethylene terephthalamide (Nylon 6T), polyhexamethylene isophthalamide (Nylon 6I), poly(2-methylpentamethylene) terephthalamide (Nylon M5T) and poly(2-methylpentamethylene) isophthalamide (Nylon M5I); and copolymers such as Nylon 6T/6I and Nylon 6T/M5T may be proposed.
Further, as the polyamide, one or more selected from an open-ring polymer of cyclic lactam, a polycondensate of aminocarboxylic acid and a copolymer thereof such as an aliphatic polyamide resin and copolymers thereof such as Nylon 6, poly-xcfx89-undecanamide (Nylon 11) and poly-xcfx89-dodecamide (Nylon 12); and a copolymer with a polyamide comprising dicarboxylic acid and a diamine such as Nylon 6T/6, Nylon 6T/11, Nylon 6T/12, Nylon 6T/6I/12 and Nylon 6T/6I/610/12 may be proposed.
As the styrene polymer, a polymer of styrene and a styrene derivative such as an a-substituted styrene and a nuclear-substituted styrene and a copolymer prepared from the above monomer with another monomer such as a vinyl compound (including acrylonitrile, acrylic acid and methacrylic acid) and/or a conjugated diene compound (such as butadiene and isoprene) may be proposed. As the styrene polymer, polystyrene, high-impact polystyrene (HIPS), acrylonitrile-butadiene-styrene copolymer (ABS resin), acrylonitrile-styrene copolymer (AS resin), styrene-methacrylate copolymer (MS resin), styrene-butadiene copolymer (SBS resin) etc. Are preferable.
Further, in order to improve the compatibility of the polyamide with the styrene polymer, a styrene copolymer in which a carboxyl-containing unsaturated compound is copolymerized may be compounded as a part of the styrene copolymer.
The styrene copolymer in which the carboxyl-containing unsaturated compound is copolymerized is a copolymer where the carboxyl-containing unsaturated compound and, if necessary, other monomer which is copolymerizable therewith is/are polymerized in the presence of a rubber polymer, and the following may be proposed.
(1) a graft polymer which is prepared by polymerizing a monomer where an aromatic vinyl is an essential component or a monomer where an aromatic vinyl and a carboxyl-containing unsaturated compound are essential components in the presence of a rubber polymer copolymerized with a carboxyl-containing unsaturated copolymer;
(2) a graft copolymer which is prepared by copolymerizing a monomer where an aromatic vinyl and a carboxyl-containing unsaturated compound are essential components in the presence of a rubber polymer;
(3) a mixture of a rubber-enriched styrene resin where a carboxyl-containing unsaturated compound is not copolymerized and a monomer where an aromatic vinyl and a carboxyl-containing unsaturated compound are essential components;
(4) a mixture of the above (1) and (2) and a copolymer where an aromatic vinyl and a carboxyl-containing unsaturated compound are essential components; and
(5) a mixture of the above (l)-(4) and a copolymer where an aromatic vinyl is an essential component.
In the above-mentioned (l)-(5), styrene is preferable as an aromatic vinyl, while acrylonitrile is preferable as a monomer which is copolymerized with the aromatic vinyl. The amount of the styrene polymer in which the carboxyl-containing unsaturated compound is copolymerized in the component (A) is preferably 0.1-8% by weight, and more preferably 0.2-7% by weight.
The amount of the component (A) in the composition is 90-30% by weight, preferably 90-40% by weight, and more preferably, 90-50% by weight.
As the fibrous filler which is the component (B) used in the present invention, carbon fiber, glass fiber and other inorganic fibers (such as silicon carbide fiber and alumina fiber) may be proposed. Among them, carbon fiber is preferable when the manufacturing cost and the reinforcing effect are taken into consideration. As the carbon fiber, carbon fibers of a cellulose, a PAN, a pitch etc. May be proposed.
The amount of the component (B) in the composition is 5-60% by weight, preferably 5-50% by weight and more preferably 5-40% by weight, so that the fluidity of the composition and mechanical strength of the molded product, etc. Are synergistically heightened by combination with the component (C).
The whisker which is the component (C) used in the present invention is a component which achieves a synergistic effect by combination with the component (B), particularly with carbon fiber and may be a metal or non-metal. For example, aluminum borate, silicon carbide, silicon nitride, potassium titanate, basic magnesium sulfate, zinc oxide, graphite, magnesia, calcium sulfate, sodium calcium phosphate, magnesium borate, titanium diborate, xcex1-alumina, chrysotile, wollastonite, etc. May be proposed.
Since the whisker is to suppress the increase of the total volume of the composition and to improve the fluidity, the more its specific gravity, the better. The gravity of the whisker is preferably 2 or more, 2.5 or more is more preferable and 2.9 or more is further preferable.
The amount of the component (C) in the composition is 5-60% by weight, preferably 5-50% by weight and more preferably 5-30% by weight, so that fluidity of the composition, mechanical strength of the molded product, etc. Are synergistically heightened by combination with the component (B).
Besides the above components (A)-(C), a flame retardant may also be compounded in the present invention, and as the flame retardant, one or more selected from a red phosphorous flame retardant and a hydrated metal flame retardant are preferable.
Examples of the red phosphorous flame retardant are red phosphorus and a compound containing phosphorus. With regard to red phosphorus, that where yellow phosphorus is converted and then disintegrated, that where the state of white phosphorus before conversion is finely classified and then converted, etc., may be used. That where the surface is untreated and that containing black phosphorus as a result of aged-based change may be also used. With regard to a compound containing phosphorus, that which contains 10% by weight or more phosphorus is preferable. When safety etc. Are taken into consideration, it is preferable that the red phosphorus and phosphorus-containing compound is made into a master batch using a base resin.
As the hydrated metal flame retardant, one or more selected from alkaline metal hydrate, hydrate of an alkaline earth metal such as aluminum hydroxide and magnesium hydroxide, and the like may be proposed. Among them, magnesium hydroxide is preferable.
The amount of the flame retardant in the composition is preferably 5-50 parts by weight, more preferably, 5-20 parts by weight, to 100 parts by weight of the total amount of the components (A)-(C).
If necessary, the composition of the present invention may be further compounded with a flame retardant other than the above-mentioned ones (inorganic flame retardants such as bromine, chlorine and antimony trioxide flame retardants), a stabilizer against heat, light and oxygen (an antioxidant such as a phenol compound and a phosphorus compound; ultraviolet absorber such as a benzotriazole compound, a benzophenone compound and a phenyl salicylate compound; and a stabilizer against heat such as a stabilizer of a hindered amine, a tin compound and an epoxy compound), a plasticizer, a slidability improving agent such as dimethyl polysiloxane, a lubricant or a mold lubricant, an antistatic agent, a coloring agent, etc.
The molded product of the present invention can be prepared by molding the above-mentioned thermoplastic resin composition by means of various molding methods such as an extrusion molding and an injection molding. Further, the molded product of the present invention may, if necessary, be subjected to known metal plating methods such as an electric plating, a nonelectrolytic plating, a melt plating, an impact plating, a vacuum plating and a chemical plating, so that the surface of the molded product is plated with metal. The molded product according to the present invention is useful as housings and parts of electric appliances for home use and office automation instruments, and the metal-plated molded products are particularly excellent in flame resistance.